Medication errors and preventable adverse drug events occur commonly among patients in the ambulatory setting and constitute an important target for patient safety and quality improvement. Laboratory monitoring to ensure the safety and effectiveness of drug therapy and the timely management of abnormal results of laboratory testing have been increasingly recognized as important areas for improving patient safety in ambulatory care. Promising interventions have been developed for practices affiliated with hospitals and integrated delivery systems, but efforts to date have not adequately reached physicians practicing solo or in small practices in the community. The Massachusetts e-Health Collaborative (MAeHC;www.maehc.org) provides an important opportunity to study implementation of healthcare information technology innovations in a community setting. In 2007, the MAeHC will complete the implementation of commercially available electronic health records (EHRs) for 441 physicians in more than 200 office practices in three diverse communities in Massachusetts. In this group of small-to-medium sized office practices in both urban and rural regions of the State, we propose a cluster-randomized controlled trial (RCT) of computerized point-of-care alerts in the EHR to prevent errors related to laboratory monitoring at the initiation and continuation of drug therapy and a results management system to prevent errors related to the delay in follow-up of abnormal laboratory testing. We will: 1) identify the barriers to and facilitators of laboratory monitoring and timely follow- up of abnormal laboratory results, especially for elderly patients and clinical scenarios common to this population;2) design, implement and evaluate the effectiveness of clinical decision support (point-of-care alerts) for laboratory monitoring in a widely used, commercially available EHR;3) design, implement and evaluate the effectiveness of a results management system to improve the timely follow-up of abnormal laboratory test results in office practice;4) develop a practical dissemination guide to assist other practices and communities interested in implementing similar interventions. The results of this study will be important because they will demonstrate and accelerate the dissemination of clinicians'use of healthcare information technology to improve patient safety and healthcare quality beyond integrated delivery systems and should be broadly generalizable to small- and medium-sized office practices in community settings. 1 Improving Laboratory Monitoring in Community Practices: A Randomized Trial. Medication errors occur frequently among patients in the ambulatory setting and cause many preventable adverse drug events;thus, they constitute an important target for patient safety and quality improvement. We propose a community-based randomized controlled trial of clinical-decision support to improve laboratory monitoring of medication use and a results management program to improve the timely follow-up of abnormal laboratory tests. This practical clinical trial will evaluate the effectiveness of promoting clinicians'use of commercially available healthcare information technology to improve medication safety in the ambulatory care setting.